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  • 1
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Entomology 27 (1982), S. 97-117 
    ISSN: 0066-4170
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 335 (1988), S. 64-66 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The Flathead River, a major tributary of the Clark Fork of the Columbia, drains a catchment area of 22,241 km2 (average flow = 340 m3 s"1) in northwestern Montana and southeastern British Columbia. The morphology and surficial geology of the Kalispell Valley (Fig. 1) were largely determined by ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2072
    Keywords: Key words Clozapine ; Haloperidol ; Subchronic ; Tolerance ; Forelimb ; Force ; Tremor ; Neuroleptics ; Atypical ; Antipsychotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  In order to compare and contrast the behavioral effects of the typical neuroleptic haloperidol with the atypical neuroleptic clozapine, ten daily doses of these drugs were administered to separate groups of rats trained to extend the forelimb through a rectangular hole and to exert downward pressure on a force transducer to gain access to water. Doses were individually titrated daily for each rat in an attempt to achieve a 50% reduction in time on task (analogous to response rate) during 8-min daily sessions. Clozapine-treated rats exhibited dramatic tolerance to the drug’s suppressive effect on time on task. In contrast, haloperidol rats displayed little tolerance on this measure. Despite the tolerance reflected by time on task, no tolerance was seen in clozapine’s marked slowing of the dominant frequency of oscillations in forelimb force as measured by Fourier analysis of the force-time recordings. Haloperidol did not slow the dominant frequency. No tolerance was seen for clozapine’s effects on forelimb force or tremor measures. Haloperidol did not significantly affect forelimb force. Both haloperidol and clozapine produced increases in the duration of long-duration forelimb responses, and no tolerance was seen for either drug on this measure of behavior. For clozapine, the dissociation between the tendency to respond (time on task) and the observed slowing of the dominant frequency may reflect effects peculiar to atypical neuroleptics, while the lengthening of long-duration responses by both drugs may reflect a more general behavioral effect that is characteristic of both typical and atypical antipsychotic drugs.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2072
    Keywords: Key words Benzodiazepine ; Operant ; Force ; Tolerance ; Chronic ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Several benzodiazepines (BZs) have been shown to increase the peak force of operant responses at doses that increased, decreased, or had no effect on response rate, suggesting that operant response force may be a sensitive index of BZs’ effects rather than solely a correlate of rate-dependent effects. In addition, contingent tolerance to the rate-dependent effects of BZs has been reported, but the degree of contingent tolerance that develops when the critical variable of the task is force of the response has not been explored. Objectives: These experiments examined the effects of acute and repeated oral administration of diazepam (DZ) and midazolam (MZ) on a force-differentiation task to explore the importance of task requirements on the development of contingent tolerance. Methods: Two groups of rats were trained to press a force-sensing operandum, and responses having peak forces falling within fixed lower and upper limits [low force (8–10 g) or high force (40–50 g)] were reinforced with water. Acute effects of the oral administration of DZ (0.3, 1.0, 3.0, 10.0, 30.0 mg/kg) and MZ (same doses) were determined for the discriminated-force task before and after a repeated-administration procedure. Results: When administered acutely, both drugs increased the peak force of responses in a dose-related manner and concomitantly reduced the proportion of reinforced responses, with MZ exhibiting greater potency. For the next 36 days, one group received drug before experimental sessions and the other group received drug after the experimental session. A second dose–effect determination demonstrated that rats chronically dosed with DZ or MZ pre-session displayed more contingent tolerance to alterations in peak force than rats that had received 36 drug injections post- session, where there was no opportunity to practice the force-discrimination response while under the drug state. Conclusions: These results suggest that perceptual motor difficulty of the task rather than effort may be an important variable in predicting the degree of contingent tolerance that develops. Additionally, these results suggest that both behavioral and pharmacological mechanisms are involved in the development of drug tolerance to the BZs.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 287 (1994), S. 11-17 
    ISSN: 1573-5117
    Keywords: hyporheic ; floodplain aquifer ; interstitial
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Interstitial crustaceans were collected from a grid of shallow sampling wells penetrating the alluvial floodplain aquifer (ca. 10 m × 5 km × 10 km) of the Flathead River, Montana, USA. Eighteen taxa were identified, which collectively encompassed a range of hypogean-epigean affinities. The subterranean amphipod Stygobromus spp., the most common crustacean, occurred in all wells but was rare in the channel well. When well data were pooled into ‘habitat types’ (channel, bank, near-, central-, and far-floodplain), distinct faunal patterns were apparent. Crustaceans constituted an increasing percentage of the total interstitial fauna from the channel to the near-floodplain, then maintained similar relative abundance levels with increasing distance from the river. Stygobionts attained maximum values at near- and central-floodplain habitats where copepods and ostracods dropped to the lowest levels. Distribution and abundance patterns of Crustacea at the floodplain scale are structured by hydrogeologic and geomorphic processes reflected only in part by distance from the river channel. The flood plain appears to contain a latticework of alluvial-filled paleochannels of high hydraulic conductivity that induce spatial discontinuities within the aquifer and that may play an important role in determining crustacean distribution patterns.
    Type of Medium: Electronic Resource
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